Alternating-current motor



T. J. MURPHY.

ALTERNATING CURRENT MOTOR.

APPLICATION FILED JUNE 2!, 1917.

1,41 9,749. ate ted J um: 13, 1922.

IN VEN TOR.

1720112415 J I? W H7 61 0 W Z&S A TTORNE;YS.-

WITNESSES:

UNITED STATES;-

PATENT OFFICE.

rnouas .1. MURPHY, or noonnsrea, NEW-YORK, ASSIGNOR or bNE-H-QLF 'ro.mmns

- an. DUFFY, or noonns'rnn, NEW YORK- ALTERNATING-CURRENT MOTOR.

Patented e 13, 1922.

Applicationfilcd June 21, 1917. Serial No. 176,221.

To aZZ whom it may concern:

Be it known that I, THOMAS J. MURPHY,

a subject of the King of Great Britain, re-

siding at Rochester, in the county of Monroe and State of New York, haveinvented cermotors and has reference particularly to a type ofconstruction coming within the general class of induction motors,wherein there is provided a stator affording a shifting magnetic field,acting upona cooperating rotor, the movement of which is roduced bycurrents set up in it by the shifting magnetic field and reacting uponthe field. The purpose of my invention is to provide a slow speed motorwhich "can be retarded,'speeded up, or reversed with great facility.Another object of the invention is to afford, a 'cheap construction,which is mechanically simple,

- so as to bring it within range of 'a large variety of applicationswhere expensive motor installatlonsand up-keep 1s prohibitive. To theseand other ends the invention "con sists in certain improvements andcombina tions of parts, all as will be hereinafter more fully described,the novel features being pointed out in the. claims at specification. pIn the drawings: q

Figure 1 is a sectional viewillustrating one application of theinvention, as an example of its possible uses, and I Figure 2 is ahorizontal sectional view of Figure 1, largely diagrammatic, andillustrating the arrangement of circuits.

Similar reference characters throughout I the several views indicate thesame parts.

The invention may be carried out in a number of different ways and issusceptible of adoption 'fOI' Il11IIlel011S purposes, and I haveillustrated by .wayof example one of its large fields of usefulness, inthe driving operation of a record support or table in sound or musicreproducing apparatus. In such instances, the motor can readily bedesigned for a speed such that no reduction gearing is necessary, therecord beingdriven the" end of the at the same speed asthe rotor. Thepresent structure eliminates the objectionable noise incidental to otherforms of electrically driven sound reproducing apparatus, and moreoverpresents an exceedingly economical arrangement which can be easilyadjusted to suit changing requirements.

In the embodiment illustrated, 1 designates a stationary base or supportupon I which the field magnets are mounted, while 2 is a frame or spiderwhich carries the rotor and is fixedupon a spindle 3 journaled-in asocket 4 of the base 1. The rotor consists of a relatively thin plate ofdiamagneticmaterial such as copper or aluminum, ref: erably 1n the formofa ring or annu us 5 which is carried [upon the frame 2. In the presentinstance, the latter also constitutes the table or support-for a discrecord of a sound reproducing apparatus, although this disposed'uponopposite sides of the rotor and in close proximity to its oppositesurfaces; The field magnets 6 may be laminated and radially slotted andare adjustable with referenceto each other, but normally disposed instaggered relation to each other so that the teeth or'projections of onemagnet are directly oppositethe winding spaces orTslots of the-oppositemagnet. To this end the outer magnet is held in place by the bolts 7cooperating with slots 8 so that by moving the bolts lengthwise of theslots,-

the outer stator unit or field magnet can be brought into varyingrelation with the inner or opposite magnet, and under ordinary operatingconditions, one magnet is positioned with reference to the othersubstantially as shown in Figure 2, the purpose of which will appear ina moment.

With the parts arranged as described, alternating current is fed to thefield magnets, so as to present the maximum intensity first upon oneside of the rotor and thereafter upon the other side, through thealternating poles, and the current set up in the rotor reacts upon thefield magnets. in such a way as to have imparted to it a series ofsuccessive impulses producing a continuous movement. To effect this,there is produced a difference in phase of magnetic flux from the twofield magnets, and this may be accomplished in different ways. As anillustration of one efficient method of accomplishing it, I have shown aresistance element which is non-inductive and arranged in parallelacrossthe circuit leading to one of the field magnets. The circuit isdesignated generally at C, being supplied from any suitable source ofalternating current, which passes b conductor C to the outer fieldmagnet, tfience by conductor C to the resistance element R and to theinner field magnet, and from there through conductor C to the other sideof the line. Thus the phase of the current in one magnet is dis placedwith reference to that in the other, so that in passing through the onemagnet it lags somewhat behind the other. This may also be accomplishedby employinga twophase current for the different magnets, or by usingferric'metals of different hysteresis losses for the inner and outermagnets. Also the windings may be different on the inner and outermagnets, to increase the difference in phase of the magnetizing current,or one magnet may be provided with greater self induction than theother, as by partially or entirely closing the radial slots at the outeredge.

motive power, the statormay include com- And to obtain increased pleterings, instead of segmental magnets as herein shown. v

By adjusting the outer field magnet with reference to the inner one, thespeed of the rotor can be reduced until the poles of one magnet areexactly opposite the polesof the other, at which point no movement willtake place and if the adjustment is carried still further, the effect isto move the rotor in the opposite direction from its previous directionof travel and thus reverse the motor. By the adjustment of the outerfield relative to the inner if the electrical phase dis placement in theinner and outer windings be regarded as constant then the synchronousspeed of the motor is changed.

I claim as my invention:

1. An induction motor comprising an an nular rotor, field magnetsdisposed on opposite sides thereof having cores of metals characterizedby different hysteresis losses for producing a shifting field, andadjust able means for varying the relative positions of said magnets andthereby controlling the speed of rotation of said rotor.

2. An induction motor comprising a rotor movable between oppositelyarranged field magnets, the magnets on opposite sides of the rotorcomprising laminae of metals having different hysteresis losses.

THOMAS J. MURPHY.

